


The Barnacle Advantage

by walking_tornado



Category: Supernatural
Genre: M/M, Masturbation
Language: English
Status: Completed
Published: 2016-02-05
Updated: 2016-02-05
Packaged: 2018-05-18 10:52:16
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,650
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5925781
Author URL: https://archiveofourown.org/users/walking_tornado/pseuds/walking_tornado
Summary: <blockquote class="userstuff">
              <p>Cas reveals to Sam and Dean little-known facts about sex in the animal kingdom.</p>
            </blockquote>





	The Barnacle Advantage

Sam jumped when Castiel appeared beside him, banging his knees against the too-small table in their unremarkable Wisconsin motel. 

"Shit, Cas, don't do that, man," Dean said from across the table. "We talked about the personal space thing already. You get that it applies to Sam, too, right?" 

"Of course. Sorry." 

Sam didn't think Cas sounded sorry at all. Sam attempted to re-read what he thought might be a key passage from a hunter's journal from the Forties, but Cas still stared. It was distracting. 

"Cas?" Sam asked. "Did you find something to help explain what's been—" 

"Did you know the antechinus has sex nonstop until it dies from exhaustion?" Cas said, as he narrowed his unblinking eyes, and then gave Sam a little nod as if he had passed along vital information. Then he disappeared. 

"Uhh. . ." Sam blinked at the now-empty space and turned to look at Dean, who shrugged with an incredulous laugh. "What was that?" 

"Who the hell knows," Dean said, and then with a little smirk, he turned his attention back to his research. With a shake of his head, Sam returned to the hunter's journal, trying to remember where he was in the text.

* * *

Sam was almost finished skimming through the journal, and he'd decided that it was little more that the ravings of a sick serial killer. Stuff like that did happen from time to time, but it was harder to identify in the hunter community because of the nature of the job. A shadow fell across the table and Cas stood across from him, staring. Again. 

"Barnacle penises are eight times their body length," Cas said. Both Winchesters' heads darted up, and Dean's glass sounded loudly as he set it down. "Several different animal species have a prehensile penis." Cas nodded his head as if underlining a point. Sam's face scrunched up in confusion as he tried to see how that had anything to do with the increased demon presence in Milwaukee. He pretended to ignore Dean, who snorted with laughter from his side of the table when Cas continued, "and flatworms have genitalia in their mouths." 

Sam's mouth dropped open and then snapped shut, and he glanced at Dean, hoping for an explanation of Cas' weird trivia. Dean sported a bemused smile and shrugged as he looked at Cas, but Cas only watched Sam. 

"Did you know that, as a celestial being, this is not my true form?" 

"Uh. . . yeah," Sam said after a moment, when he realized that Cas was actually waiting for an answer. Cas smiled and vanished. 

* * *

Sam had put aside the serial killer's manifesto, having bookmarked the one possibly relevant section, and was now flipping through a psychologist's experiment notes from 1936 when Cas reappeared. 

"Bonobos are bisexual. And so are deep sea squid. " 

"Wait," Sam said, throwing up his hand to stop Cas from continuing as well as pre-empt whatever Dean was about to say. When Dean wore that wide a grin, Sam knew he didn't want to hear it. "Cas, are you trying to tell us that the Milwaukee demon possessions are because of some strange sex-thing?" 

Cas gave him a thin-lipped, reproachful look. "Gender doesn't even have meaning for fungi. Does it really matter that much for humans?" 

Sam shook his head. "I don't understand what this has to do with—" Cas disappeared again. 

* * *

"Snakes have two penises." 

Sam jumped when Cas appeared less than a finger's breadth away, and he casually moved his hands, hoping to prevent Cas from seeing his hard-on. With the talk about sex, Sam had reread the same paragraph six times now. He'd have gone to the bathroom to take care of it earlier, but he'd have to walk by Dean, who would definitely notice and who would make it his brotherly duty to never let Sam live it down. 

"Echidna penises have four heads," Cas told him, and Sam felt as if that piercing stare saw everything he might want to hide. Then Sam and Dean were alone again. 

"Okay, he's kind of freaking me out with the sex stuff," Dean said. "What do you think he's doing when he's not here? Is this like a personal experience thing? No! No, forget I even asked. So not going there." Dean shook his head as if to do an Etch-a-Sketch erase, and went to refill his glass. 

Sam squirmed and pressed the heel of his palm against his erection, which didn't help at all. 

Dean set his refilled drink on the table and sat heavily in the chair. 

"I'm getting nowhere with this. You?" he asked. 

Sam closed his book. "Nothing." 

"All that animal stuff—who'd have thought I'd get shown up by a frigging barnacle." 

Sam either needed everyone to stop talking about sex or he needed to escape to the bathroom to think about it exclusively. He grabbed a book and was about to risk going past Dean when Cas appeared, close by and blocking his route. 

"Did you know sometimes a dolphin will penetrate another male dolphin through its blowhole?" 

"Okay, that's it!" Dean stood up, raising his hands as if he wanted to cover his ears. "Sam, I'm going to take a walk down the road to get us supper. And Cas, when I get back, you'll have quit it with the fucked-up nature interludes. It's fucking weird." He strode to the door, his decisive stride narrowly missing being a run. The door banged shut. 

Sam started as Cas suddenly filled his vision, standing much too close. 

"But that's just it Sam!" Cas' stare intensified. "That's what I've been saying. It's not weird. It's good—and perfectly normal! Sex is a gift to the world, a marvelous gift! But," he grimaced his frustration, "you're not using it!" 

Sam's mouth had dropped open and he stared back, frozen. Cas pinched his lips in consternation, before he fixed his gaze to Sam again and in a smooth motion, Cas unzipped his pants and pulled out his engorged cock. 

"What—Where—What are you doing?" Sam said, his voice more high-pitched than usual. 

"Masturbating. There's a video of a dolphin using a fish to masturbate. Would you like me to show you?" 

"No! God, no!" Sam quickly shook his head and his eyes flew up to meet Cas' serene gaze before falling down to where Cas had casually begun working his cock. The wet glistening tip slipped from view, only to reappear as Cas brought his hand down and gave a slow thrust of his hips. He removed his hand to lick his palm and returned to pump it quickly before he slowed down again. 

"It's better when wet," Cas told him, matter-of-fact. 

"Yeah," Sam said on an exhale, "I know." 

Cas' breathing had sped up and his eyelids had sunk down, but he still watched Sam. 

"Cas?" Sam whispered. He hadn't thought that the angel would have known the first thing about pleasuring himself. 

"Much of it is instinct and muscle memory, Sam," Cas said. "And I am responsible my vessel's proper maintenance, so I study it. Granted, this body is not quite up to barnacle standards," Cas shrugged, "but it does have a few good features, doesn't it?" The question would have sounded insecure coming from anyone else, but from Cas it sounded like an honest question. 

"Sure, it's fine," Sam stammered. 

"Good," Cas said. For a moment there was no sound but the squelch of Cas' hand working his cock. "I know you like this, Sam," Cas said. "I can hear your thoughts, every time you think of me. It's like when you pray." 

Sam felt the blood rush to his face, but it didn't affect his insistent hard-on. 

"I like how this vessel feels. Do you?" Without taking his eyes away from Sam, Cas reached down to take Sam's hand, and he placed it on his cock. Sam's breath trembled as he exhaled. He let his thumb trace the flared ridge and wrapped his hand tighter around the warm shaft. He felt the prominent vein against his palm as he slid his hand down, and Cas gave a small thrust. "Now you," Cas said. 

"What?" Sam's hand stuttered in its motion. Cas frowned at him. 

"Penguins—" Cas began, but Sam cut him off and stood up. 

"No, yeah, I got it." He met Cas' gaze, reached down, and released his cock from the painful confines of his jeans. Sam took a step forward and crowded Cas into the wall, where he braced himself with a hand on either side of Cas' head. Sam bent his knees to line up their cocks and before he could give a hesitant thrust into the junction of Cas' thigh, Cas wrapped his hand around both their cocks. Sam groaned. It didn't take long before the hot pressure of Cas' hand, the feel of Cas' cock next to his, had Sam's eyes rolling back in pleasure as his climax overtook him. Cas immediately followed. 

Sam panted from his exertions, and his knees threatened to collapse but he stayed upright, taking a heavy step away from Cas. Cas gave him an evaluating look while he raised his hand and sniffed at their combined release, before his tongue came out for a taste. Sam held his breath as Cas smiled and took a step towards him. 

"I don't think we're done yet, Sam." 

Sam's eyes drifted to the door. "Dean . . ." 

Cas tilted his head. "Dean is . . . interviewing . . . a waitress who just finished her shift." He looked toward the wall and his eyes seemed fixed on a faraway point. Then he gave a fond smile. "He seems to have taken issue with my barnacle. He will definitely be awhile." Cas took two steps towards the bed, and Sam found himself following. "Did you know," Cas asked him, "that some rodents, like the Shaw's jird, can copulate over a hundred times an hour?"

end

**Author's Note:**

> Written for [THIS](http://spn-masquerade.livejournal.com/6017.html?thread=1824385#t1824385) prompt during the last round of spn_masquerade. Thanks to firesign10 for the beta!


End file.
